Key result
Phase-rectified signal averaging decelerative capacity predicted fetal acidaemia better than short-term variation.
Why the study?
Does PRSA decelerative capacity predict intrapartum acidaemia better than short-term variation in fetal heart rate monitoring?
Cohort (n=7,568)
No
Does PRSA decelerative capacity predict intrapartum acidaemia better than short-term variation in fetal heart rate monitoring?
Phase-rectified signal averaging of fetal heart rate during labor predicts acidaemia at birth more accurately than short-term variation.
Answers are grounded in this paper and cite their sources.
May support PRSA evaluation for intrapartum monitoring; leaves open prospective validation before any practice change.
OBJECTIVE: Recent studies suggest that phase-rectified signal averaging (PRSA), measured in antepartum fetal heart rate (FHR) traces, may sensitively indicate fetal status; however, its value has not been assessed during labour. We determined whether PRSA relates to acidaemia in labour, and compare its performance to short-term variation (STV), a related computerised FHR feature. DESIGN: Historical cohort. SETTING: Large UK teaching hospital. POPULATION: All 7568 Oxford deliveries that met the study criteria from April 1993 to February 2008. METHODS: We analysed the last 30 minutes of the FHR and associated outcomes of infants. We used computerised analysis to calculate PRSA decelerative capacity (DC(PRSA)), and its ability to predict umbilical arterial blood pH ≤ 7.05 using receiver operator characteristic (ROC) curves and event rate estimates (EveREst). We compared DC(PRSA) with STV calculated on the same traces. MAIN OUTCOME MEASURE: Umbilical arterial blood pH ≤ 7.05. RESULTS: We found that PRSA could be measured in all cases. DC(PRSA) predicted acidaemia significantly better than STV: the area under the ROC curve was 0.665 (95% CI 0.632-0.699) for DC(PRSA), and 0.606 (0.573-0.639) for STV (P = 0.007). EveREst plots showed that in the worst fifth centile of cases, the incidence of low pH was 17.75% for DC(PRSA) but 11.00% for STV (P < 0.001). DC(PRSA) was not highly correlated with STV. CONCLUSIONS: DC(PRSA) of the FHR can be measured in labour, and appears to predict acidaemia more accurately than STV. Further prospective evaluation is warranted to assess whether this could be clinically useful. The weak correlation between DC(PRSA) and STV suggests that they could be combined in multivariate FHR analyses.
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Georgieva et al. (2014) conducted a cohort in Fetal acidaemia during labour (n=7,568). Phase-rectified signal averaging (PRSA) decelerative capacity vs. Short-term variation (STV) was evaluated on Umbilical arterial blood pH ≤ 7.05 (AUC 0.665, 95% CI 0.632-0.699, p=0.007). Phase-rectified signal averaging decelerative capacity predicted fetal acidaemia better than short-term variation.
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